Strange slime covering parts of Jefferson Memorial

The Jefferson Memorial in Washington, D.C. was once a shiny white monument, but over the past decade or so its dome has developed quite a patina, notes Sky News.

While aged finishes are desirable in some situations, this is not one of them.

According to Popular Science, in 2014, experts were tasked with removing the dark film, but are struggling to figure out how they're going to make that happen.

The covering has been identified as a biofilm, and the microbes residing on the monument's surface are proving difficult to evict.

Just going after the gunk with some bleach and a scrub brush isn't an option, as that could cause harm to the marble surface.

Lasers are being considered as an option, as are a variety of chemical concoctions currently being tested by the conservation team.

Federica Villa, one of the microbiologists working on the project said, "To be honest, we have a lot of work to do."

While no solution has yet been determined, the restorers remain hopeful one will eventually appear.

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